Optical information medium

ABSTRACT

An optical information medium having an ink-accepting layer that may secure a high-gloss printed surface similar to print image quality of print image on photographic paper is provided. The optical disk 1 is constituted by sequentially laminating concavo-convex information pits  3,  a recording layer  4,  a reflective layer  5,  a protective layer  6,  a second printing layer  7,  and an ink-accepting layer  8  on a transparent substrate  2  made of synthetic resin such as polycarbonate.  
     In formation of the above described ink-accepting layer  8,    
     A. Urethane acrylate: 5 to 15  
     B. Water-soluble monomer: 70 to 80  
     C. Water-soluble monomer soluble resin: 5 to 15  
     D. Photopolymerization initiator: 5 to 15  
     E. Dyestuff fixing agent: 5 to 15  
     F. Silica: &lt;5  
     were milled to prepare an ink for printing (unit; percent by weight).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to optical recording medium havingprinted layer with ink which has writability.

[0003] 2. Description of the Related Art

[0004] In some of recording media, in which playback or record is madeby laser light, for example, CD-R (Compact Disc Recordable) having arecording layer in which rewriting of one time or multiple times by useris possible, an entry area in which so-called personal information, suchas titles of records, date of record, etc. can be filled in by user withcharacters, symbols, etc. is provided on a side opposite to an incidentside of laser light of this recording medium. In this entry area methodsof entry by handwriting with a felt pen, by ink jet recording, so-calledjet printing, or by transferring of colored ink by heat and pressureapplied to a film having a colored ink layer may be applicable.

[0005] Then, such proposal of providing a personal information entryarea constituted by an ink-accepting layer currently prepared so thatentry of personal information etc. by the above described felt pen orjet printer, transferring of colored ink by film having colored inklayer, etc. may be sufficiently enabled over a recording medium has beenmade.

[0006] In recent years, use of multiple ink nozzles makes multi-colorrecording having higher definition easier, and especially multi-colorink jet recording by various kinds of ink jet recording systems werecarried out. In recent years printers used for ink jet recording hasbecome to have high performance, and quality improvement ofink-accepting layer of the above described area for entry of personalinformation has become to be required. Namely, bleeding stability ofprinted image, and securing of high-gloss printed surface similar toprint image quality of print image on photographic paper by highlyglossed ink-accepting layer resulting from smoothness of printed surfacehave been demanded.

[0007] However, conventionally, in plenty of cases, ink for ink jetrecordings for recording on this ink-accepting layer has a constitutionin which polyhydric alcohol etc. is added to water ink mainly includingwater as principal component in order to avoid clogging of nozzle, andto improve ejecting characteristics, for safety and recordcharacteristics. Therefore, for the purpose of eliminating stickinessfor strong adhesion of dyestuff in the ink, for quick absorption ofwater in the ink, and for improvement in handling property, anink-accepting layer currently formed in optical recording media, such asCD-R, includes a large amount of commonly known fillers, such as silica,talc, clay, zeolite, calcium carbonate, calcium silicate, magnesiumcarbonate, barium sulfate, mica, synthetic mica, diatomaceous earth,aluminum hydroxide, titanium oxide, powder cellulose, and powderprotein. Therefore, front face of the ink-accepting layer tends to berough, and an ink-accepting layer in which high-gloss printed surfacesimilar to print image quality of print image on photographic paper issecured has not yet been realized.

[0008] The present invention is made in view of such conventional actualsituation, and aims at providing an optical information medium providedwith an ink-accepting layer in which high-gloss printed surface similarto print image quality of print image on photographic paper is secured.

SUMMARY OF THE INVENTION

[0009] In order to solve the above described subject, in an informationrecording medium having an ink-accepting layer on which printing orwriting is enabled on front face of the present invention, glossiness ofa front face of the above described accepting layer represented with avalue measured under 60-degree glossiness value conditions in opticalcharacteristic test method of plastics in JIS-K 7105 is set so that itmight give not less than 40 degrees.

[0010] Since the above described surface glossiness was set as not lessthan 40 degrees, better visual glossiness is secured as compared withconventional ink-accepting layers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view showing an optical disk according toa first embodiment of the present invention;

[0012]FIG. 2 is an expanded sectional view of the optical disk;

[0013]FIG. 3 is a graph showing measurement results of surface roughnessRa in each glossiness value of ink-accepting layers (arithmetic meanrelative roughness);

[0014]FIG. 4 is a perspective view showing an optical disk in which kindof optical disk, capacity, maker name, and other character and patternare printed on an upper layer of an ink-accepting layer; and

[0015]FIG. 5 is a perspective view showing a card type recording mediumto which the present invention may be applied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

[0016]FIG. 1 is a perspective view of information recording medium(hereinafter, referred to as optical disk) 1 of the shape of a disk ofthe present invention. This optical disk 1 has an ink-accepting layer 8on a front face. FIG. 2 is an expanded sectional view of the abovedescribed optical disk 1. The optical disk 1 is constituted bysequentially laminating a concavo-convex information (pit) 3, arecording layer 4, a reflective layer 5, a protective layer 6, a secondprinting layer 7, and an ink-accepting layer 8 on a transparentsubstrate 2 made of synthetic resin such as polycarbonate.

[0017] Then, detailed description of the second printing layer 7 and theink-accepting layer 8 will be given.

[0018] Although the above described second printing layer 7 is formedusing UV DVC-616 white (manufactured by Teikoku Printing Inks Mfg. Co.,Ltd.), in addition, inks for UV curing type screen-printing for opticalrecording media including not less than 10% of titanium oxide may beused. And, inks which have ink acceptance also in themselves may be usedas this white ink.

[0019] And this ink for printing of the second white printing layer 7was printed on a UV resin topcoat layer as the above describedprotective layer 6 to give an applied thickness of 8 micrometers using apolyester screen having 350 mesh/inch, 31 micrometers of yarn diameter,and openings of 38 micrometers, subsequently ultraviolet radiation of300 mJ/square cm was irradiated using a metal halide lamp, and a printedsurface was cured to form the second white printing layer 7. Information of the above described ink-accepting layer 8,

[0020] A. Urethane acrylate: 5 to 15

[0021] B. Water-soluble monomer: 70 to 80

[0022] C. Water-soluble monomer soluble resin: 5 to 15

[0023] D. Photopolymerization initiator: 5 to 15

[0024] E. Dyestuff fixing agent: 5 to 15

[0025] F. Silica: <5

[0026] were milled to prepare an ink for printing (unit; percent byweight).

[0027] And this prepared ink was printed on the above described secondwhite printing layer 7 so that an applied thickness of 12 micrometersmight be given, using a Tetoron screen having 300 mesh/inch, 35micrometers of yarn diameter, and openings of 50 micrometers,subsequently ultraviolet radiation of 350 mJ/square cm was irradiatedusing a metal halide lamp, and a printed surface was cured to form anink-accepting layer 8.

[0028] A glossiness of a front face of this ink-accepting layer 8 wasmeasured under 60-degree glossiness value conditions in opticalcharacteristic test method of plastics in JIS-K 7105 to give aglossiness value of 53 degrees.

[0029] When an ink-accepting layer 8 was formed, silica was included inthe ink-accepting layer, and a value of glossiness of the ink-acceptinglayer 8 was changed by varying a content as seven levels; 2 degrees, 20degrees, 36 degrees, 45 degrees, 53 degrees, 60 degrees, and 78 degrees.Identification test was performed by ten visual testers, and a rate ofthe number of visual testers who recognized glossiness was obtained.Results shown in following Table 1. TABLE 1 Rate of tester recognizingGlossiness (degree) glossiness (%) 2 0 20 0 36 50 45 70 53 80 60 100 78100

[0030] As is clear in Table 1, in glossiness value of the ink-acceptinglayer 8 of 2 degrees and 20 degrees, a rate of visual testers whorecognized glossiness was 0%. In glossiness value of the ink-acceptinglayer 8 of 36 degrees, a rate of visual testers who recognizedglossiness was 50%, in glossiness value of the ink-accepting layer 8 of45 degrees, a rate of visual testers who recognized glossiness was 70%,in glossiness value of the ink-accepting layer 8 of 53 degrees, a rateof visual testers who recognized glossiness was 80%, in glossiness valueof the ink-accepting layer 8 of 60 degrees and 78 degrees, a rate ofvisual testers who recognized glossiness was 100%.

[0031] From the above result, it became clear that an ink-acceptinglayer 8 currently formed on the optical disk was made to have highglossiness, and that a high-gloss printing ink-accepting layer 8 similarto print image quality of print image on photographic paper wassecurable by controlling a glossiness of the ink-accepting layer 8 tonot less than 40 degrees, and preferably not less than 50 degrees.

[0032] And a gradation pattern form with gradually varying printingshade was printed onto the obtained high-gloss printing ink-acceptinglayer 8 using an ink jet printer (maker name: SEIKO EPSON CORPORATION,trade name: PM-900C), and a high-gloss printing ink-accepting layer 8 bythis embodiment having 40 degrees of glossiness values was visuallycompared with a conventional available level of article having anink-accepting layer 8 of 2 to 20 degrees of glossiness values.Consequently, also an advantage of quality of image printed on thehigh-gloss printing ink-accepting layer 8 by this embodiment wasconfirmed in ink jet printer printing quality of image.

[0033] In addition, although urethane acrylate that is a UV curableoligomer was used here as a component of ink for the ink-accepting layer8, use of UV curable oligomer of other type, such as epoxy acrylate andpolyester acrylate, may also be possible. In addition to them,components having function maintaining adhesive strength with the abovedescribed protective layer 6 or the second white printing layer 7, suchas UV curable monomer and resin may be usable.

[0034] Besides, among water-soluble monomers used as a UV curablemonomer as a diluent for UV ink are butadiene diol mono acrylate,2-hydroxyethyl acrylate, N,N-diethylamino ethyl methacrylate,N,N-diethylamino ethyl acrylate, N,N-dimethyl acrylamide, methoxy methylacrylamide, ethoxy methyl acrylamide, propoxy methyl acrylamide, butoxymethyl acrylamide, acrylyl morpholine, methoxy polyethylene glycolacrylate, 2(2-ethoxy ethoxy)ethyl acrylate, 2-hydroxyethyl vinyl ether,etc. One kind of the water-soluble monomer may be used separately, ortwo or more of them may be used in combination.

[0035] Moreover, among water-soluble monomer soluble resins used inorder to increase ink absorbing power of ink for ink jet recordings arepolyvinyl pyrrolidone, alkyl (meth)acrylate (co)polymers, vinyl chloridevinyl acetate copolymers, polyesters, cellulose acetates, cellulosepropiols, cellulose acetate butylates, cellulose nitrates, hydroxyethylcelluloses, hydroxypropyl celluloses, hydroxypropyl methyl cellulosephthalates, hydroxypropyl methyl celluloses, cellulose acetatesuccinates, ethyl celluloses, butyral resins, etc. One kind of thewater-soluble monomer soluble resins may be used separately, or two ormore of them may be used in combination.

[0036] Moreover, among photopolymerization initiators for startingpolymerization by ultraviolet radiation are benzoin ethyl ether,2-hydroxy-2-methyl-1-phenyl propane-1-on, 1-hydroxy cyclohexylphenylketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropanone-1, bisacyl phosphine oxide, etc. One kind of thephotopolymerization initiators may be used separately, or two or more ofthem may be used in combination.

[0037] Furthermore, as illustrative examples of dyestuff fixing agentsused in order to decrease bleeding of printed image and stickiness ofprinting section; Polyfix 700, Polyfix 601, Polyfix IJ-1000S (by SHOWAHIGHPOLYMER CO., LTD.); Super resist NP, SENKAFIX 157, SENKAFIX 300,SENKAFIX 401, SENKAFIX JOY-2, SENKAFIX JOY-8N, SENKAFIX NFC, SUPRAFIXDFC, CHERCUT CF-2, SILKFIX 3A, HI-16A, HP-142A, HP-144A, HP-146A,HP-149A, HP-151A (by SENKA CORPORATION ); Sanfix 70, Sanfix 414, SanfixPRO-100, Sanfix PAC-700 conc (by Sanyo Chemical Industries, Ltd.);Mohrin fix 3PN, Mohrin fix 6P, and Mohrin fix 300B (by Mohrin ChemicalIndustry, Ltd.); IJC-002, IJC-009 (by NICCA Chemical Co., Ltd.); KayafixM (by NIPPON KAYAKU CO., LTD.) etc. may be mentioned. One kind of thedyestuff fixing agents may be used separately, or two or more of themmay be used in combination.

[0038] Moreover, as for silica, it is preferable that fine-grains silicahaving a grain diameter of less than 0.1 micrometer is used in less than5 parts by weight so that it may give enough transparency not todecrease the whiteness of the second white printing layer 7, and so thatthe glossiness may not be decreased.

[0039] An ink for printing the ink-accepting layer 8 is constituted byUV curable oligomer and/or UV curable monomer, and photopolymerizationinitiator as essential components, and in addition water-soluble monomersoluble resins, leveling agents, plasticizers, antioxidants, defoamingagent, surface tension regulators, etc. may be included as an additivefor attaining stabilization of the ink etc.

[0040] Now, samples in which glossiness value of the above describedink-accepting layer 8 was prepared with the seven levels of 2 degrees,20 degrees, 36 degrees, 45 degrees, 53 degrees, 60 degrees, and 78degrees were measured for a surface roughness Ra (arithmetic meanrelative roughness) of the ink-accepting layers 8, and results are shownin FIG. 3. FIG. 3 is represented by letting X coordinate be surfaceroughness Ra (arithmetic mean relative roughness), and glossiness ofink-accepting layer 8 be Y coordinate. Measurement of surface roughnessRa (arithmetic mean relative roughness) of an ink-accepting layer 8 wasperformed by Surfcom 550A (trade name) of Tokyo-Seimitsu.

[0041] Surface roughness Ra (arithmetic mean relative roughness) of anink-accepting layer 8 and glossiness of the ink-accepting layer 8 have aclear linear relationship between them, as is apparent in FIG. 3,scattered reflection of an ink-accepting layer 8 will be suppressed, andnot less than 40 degrees of glossiness of the above describedink-accepting layer 8 may be obtained by controlling a surface roughnessRa (arithmetic mean relative roughness) of the ink-accepting layer 8 tonot more than 0.6 micrometer.

[0042] In the above described ink-accepting layer 8, although lightness(L) of the second white printing layer 7 which serves as a lower layerhaving a glossiness value of the ink-accepting layer 8 of 45 degreesshowed 91 degrees, a result of comparison by viewing of feeling ofglossiness of a second white printing layer 7 set as lightness of 87degrees, and feeling of glossiness of a second white printing layer 7having lightness of 91 degrees raised a problem that glossiness whichwas reduced in appearance in the second white printing layer 7 havinglightness of 87 degrees was observed.

[0043] In addition, as shown in FIG. 4, kind of optical disk, capacity,maker name, and other character and pattern 9 may be printed by maker onthe top of an ink-accepting layer 8.

Second Embodiment

[0044] An ink that forms an ink-accepting layer of a second embodimentof the present invention was prepared by milling a mixture having afollowing composition (unit: percent by weight).

[0045] A. Polyvinyl acetal resin: 5 to 15

[0046] B. Water: 50 to 60

[0047] C. Isopropyl alcohol: 30 to 40

[0048] D. Dyestuff fixing agent : <5

[0049] E. Silica: <5

[0050] And on the above described second white printing layer, theprepared ink was applied by flow coating so that an applicationthickness after dried may give 10 micrometers, and subsequently, driedfor 2 minutes by 60° C. warm air, and an ink-accepting layer 8 wasformed.

[0051] A glossiness of a front face of this ink-accepting layer wasmeasured under 60-degree glossiness value conditions in opticalcharacteristic test method of plastics in JIS-K 7105 to give aglossiness value of 70 degrees.

[0052] Except that a composition and a formation method of anink-accepting layer 8 of the first embodiment were changed as describedabove, the same operation as the first embodiment was repeated to obtainsame results as in Table 1 and in FIG. 3.

[0053] In addition, although polyvinyl acetal resin was used as acomponent of ink of an ink-accepting layer 8, used resin does not needto be limited to this and various kinds of hydrophilic resins havingwettability to water may be used. As examples the above describedwater-soluble monomer soluble resin etc. besides hydrophilic resins,such as polyvinyl butyrals, polyvinyl pyrrolidone, cellulose basedresins, acrylic emulsions, and polyester emulsions may be mentioned. Onekind of the resins may be used separately, or two or more of them may beused in combination.

Third Embodiment

[0054] In a third embodiment of the present invention, a constitution inwhich powder of scale-like piece, i.e., flake-like (shape of board)piece was dispersed and included in an ink forming a second printinglayer 7 under an ink-accepting layer 8. Thereby when this second whiteprinting layer 7 is printed by a method, such as screen-printing, on aprotective layer 6, ink is extruded by a squeegee from silk screen andpowder of scale-like piece dispersed and included in the ink is forcedon a front face of the protective layer 6 by pressure of squeegeeing,and thus arranged in a shape of a plate to provide a white printinglayer 7 with high lightness.

[0055] An ink forming this second white printing layer 7 of the thirdembodiment was obtained by kneading UV DVC-000 Medium (manufactured byTeikoku Printing Inks Mfg. Co., Ltd.): 75 parts by weight, as baseresin, and white mica powder having a diameter of 12 micrometers (aspectratio 5): 25 parts by weight, as powder of scale-like piece.

[0056] This ink prepared for printing for a second white printing layer7 of the third embodiment was printed so that an applied thickness of 15micrometers might be given, on a UV resin topcoat layer as the abovedescribed protective layer 6, using a Tetoron screen having 250mesh/inch, 40 micrometers of yarn diameter, and openings of 62micrometers. Subsequently ultraviolet radiation of 350 mJ/square cm wasirradiated using a metal halide lamp, and a printed surface was cured toform a white printing layer 7.

[0057] In addition, as a powder of scale-like piece included in an inkfor printing for a second white printing layer 7 of the third embodimentof the present invention, beside of the white mica powder (aspect ratio5) having a diameter of 12 micrometers illustrated as example, talc,glass flakes, board-like calcium carbonates, board-like aluminumhydroxides, kaolin, titanium oxides, etc. may be used.

[0058] Moreover, here, a description was given of an ink-accepting layer8 of optical disks represented by CD-R etc. In addition, a card typerecording medium 21 disclosed in International Laid-Open WO 099/00765 inwhich a hole 23 for driving for actuation is formed to a plate as shownin FIG. 5 also has an ink-accepting layer 22 similarly formed on a backface of an incident side 24 of light for playback/record on atransparent substrate. Also in this field, it becomes possible to supplycard-like recording medium with high commercial value.

[0059] (1) According to the invention of claim 1, in an opticalinformation medium in which an information recording layer is formed ona disk-like transparent substrate, and information optically readablewith laser light may be played back and/or recorded, surface glossinessof an ink-accepting layer having ink acceptability that is coated onto aback face of incident side of light for playback/record of the abovedescribed transparent substrate is set to not less than 40 degrees, andthereby high-gloss is given to the ink-accepting layer currently formedon an optical disk to secure a high-gloss printing ink-accepting layersimilar to print image quality of print image on photographic paper. Inthis way, a high quality of image may be obtained in a gradation patternform with gradually varying printing shade in an ink jet printer, and asa result advantage will be secured as compared with conventionalavailable level of articles also in printing quality of image by an inkjet printer, and attractiveness to consumers can be increased.

[0060] (2) According to the invention of claim 2, surface roughness Ra(arithmetic mean relative roughness) of a high-gloss printingink-accepting layer is controlled to be set to not more than 0.6micrometer, and thereby scattered reflection of the high-gloss printingink-accepting layer is suppressed to enable glossiness of theink-accepting layer stably to have not less than 40 degrees.

[0061] (3) According to the invention of claim 3, a white printing layerhaving lightness of not less than 90 degrees is prepared under ahigh-gloss printing ink-accepting layer, and thereby high glossiness inappearance is maintained as compared with the white printing layer 7having low lightness to provide a stable and high-gloss printingink-accepting layer.

[0062] (4) According to the invention of claim 4, 5 and 6 when the lowerlayer is printed by a method, such as silk printing on a protectivelayer on a lower layer of a high-gloss printing ink-accepting layer,using an ink in which powder of scale-like particles are dispersed andincluded, the ink is extruded by a squeegee from silk screen and powderof scale-like piece dispersed and included in the ink is forced on afront face of the protective layer 6 by pressure of squeegeeing, andthus arranged in a shape of a plate to obtain a ground printing layerhaving high lightness and high flatness.

[0063] (5) According to the invention of claim 7, printing is performedto a high-gloss printing ink-accepting layer by an ink containing UVcurable monomer and/or UV curable oligomer, thereby curing is performedin a short time, when the high-gloss printing ink-accepting layer isprinted onto an optical disk and cured, and furthermore generation ofVOC in curing time may also be suppressed to enable alleviation ofeffect on earth environment.

[0064] (6) According to the invention of claim 8, ink absorbing power ofan ink for ink jet recordings may be increased by applying and drying anink including hydrophilic resins and cost may be reduced as comparedwith inks including UV curable oligomer and/or UV curable monomer.

[0065] (7) According to the invention of claim 9 and 10, a little amountof silica having a grain diameter of less than 0.1 micrometer isincluded in an ink that forms a high-gloss printing ink-accepting layer,thereby thixotropic property is given to the ink for the ink-acceptinglayer to improve printability in screen-stencil, and thus a stableink-accepting layer may be formed, and furthermore absorbing power ofthe ink jet recording ink improves, and an effect of suppression ofbleeding of printed image or stickiness of printing section may beobtained by inclusion of a dyestuff fixing agent.

What is claimed is:
 1. An optical information medium in which aninformation recording layer is formed on a disk-like transparentsubstrate, and information optically readable with laser light may beplayed back and/or recorded, wherein surface glossiness of anink-accepting layer having ink acceptability coated onto a back face ofincident side of light for playback/record of the transparent substrateis set to not less than 40 degrees.
 2. The optical information mediumaccording to claim 1, wherein an average surface roughness (Ra) of theink-accepting layer is smaller than 0.6 micrometer.
 3. The opticalinformation medium according to claim 1, wherein a white printing layerhaving 90 degrees or more lightness is formed under the ink-acceptinglayer.
 4. The optical information medium according to claim 1, wherein aprinting layer is formed under the ink-accepting layer by an ink inwhich powder of scale-like particles are dispersed and included.
 5. Theoptical information medium according to claim 2, wherein a printinglayer is formed under the ink-accepting layer by an ink in which powderof scale-like particles are dispersed and included.
 6. The opticalinformation medium according to claim 3, wherein a printing layer isformed under the ink-accepting layer by an ink in which powder ofscale-like particles are dispersed and included.
 7. The opticalinformation medium according to any one of claims 1 to 6, wherein theink-accepting layer is formed by curing of an ink including UV curablemonomer and/or UV curable oligomer.
 8. The optical information mediumaccording to any one of claims 1 to 6, wherein the ink-accepting layeris formed by an ink with a hydrophilic resin dissolved in solvent beingdried.
 9. The optical information medium according to claim 7, whereinthe ink-accepting layer includes silica having a grain diameter of lessthan 0.1 micrometer and/or a dyestuff fixing agent.
 10. The opticalinformation medium according to claim 8, wherein the ink-accepting layerincludes silica having a grain diameter of less than 0.1 micrometerand/or a dyestuff fixing agent.